Display Device

ABSTRACT

A touch panel includes a plurality of first electrodes, a plurality of second electrodes, and a plurality of wirings. Each of the plurality of first electrodes has a first portion formed on a layer different from that on which the second electrodes are formed and intersecting the second electrodes, and a second portion formed on the same layer as that on which the second electrodes are formed, but separated from the second electrode. The second electrode and the second portion of the first electrode are formed on a layer upper than the layer where the wiring is formed. The first portion of the first electrode is connected to the second portion in a contact hole formed on an insulating film between the first portion and the second electrode, and formed on the same layer on which the wiring is formed.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese applicationJP2008-197240 filed on Jul. 31, 2008, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a touch panel-equipped display device,and in particular to a touch panel-equipped display device having astatic capacitance coupling type touch panel.

2. Description of the Related Art

As major types of touch panels, there are known a type for detecting anoptical change and a type for detecting change in electricalcharacteristic. As a type for detecting change in electricalcharacteristic, a static capacitance coupling type is known (seeJapanese Patent Laid-open Publication No. 2008-65748 and Japanese PatentLaid-open Publication No. 2009-015489).

According to a conventional static capacitance coupling type touchpanel, disclosed in the above-described Japanese Patent Laid-openPublication No. 2008-65748 and Japanese Patent Laid-open Publication No.2009-015489, a plurality of electrodes (X electrodes) and a plurality ofelectrodes (Y electrodes) are formed on different electricallyconductive layers (a lower layer and an upper layer), respectively, viaan insulating film. For the above described electrode structure, theinsulating film and a protective film formed on an electrode on theupper layer are distorted due to the electrode on the upper layer. Inaddition, as the optical path length for reflected light is differentbetween the lower layer and the upper layer, a color difference iscaused between an electrode on the lower layer (e.g., the X electrode)and an electrode (e.g., the Y electrode) on the upper layer, whichcauses an electrode pattern of the electrodes on the upper and lowerlayers to appear to become noticeable. An electrode pattern having beenappeared to be noticeable, as described above, will deteriorate opticalcharacteristic, resulting in deterioration in characteristic of thedisplay device with a touch panel mounted therein.

In view of the above, the present applicant has proposed a touch paneladopting a new electrode structure, and already filed a patentapplication therefor (U.S. patent application Ser. No. 12/427,878).

FIGS. 6 to 8 are diagrams related to an electrostatic capacitance typetouch panel for which the present applicant has already filed a patentapplication. In particular, FIG. 6 is a plan view showing an electrodepattern of a touch panel; FIG. 7 is a cross sectional view showing across sectional structure along the line VII-VII in FIG. 6; and FIG. 8is a cross sectional view showing a cross sectional structure along theline VIII-VIII in FIG. 6.

In the touch panel shown in FIGS. 6 to 8, an electrode 1X has a firstportion 1 a and a second portion 1 b. The first portion 1 a is formed ona layer different from the layer on which electrode 2Y is formed, so asto intersect the electrode 2Y. The second portion 1 b is formed on thesame layer as that where the electrode 2Y is formed, but separated fromthe electrode 2Y. The first portion 1 a is connected to the secondportion 1 b in a contact hole 12 a formed on an insulating film 12between the first portion 1 a and the electrode 2Y. For this electrodestructure, a protective film 13 can be formed having a consistentsurface so that the distortion of the protective film 13 can besuppressed, and therefore, appearance of an electrode pattern due tocolor difference due to distortion of the protective film 13 can besuppressed. As a result, as deterioration of optical characteristic dueto an appeared electrode pattern can be suppressed, deterioration incharacteristic of a display device with the touch panel mounted thereincan be suppressed.

Further, as a portion with color difference caused can be minimized tothe first portion 1 a of the electrode 1X alone, an appeared electrodepattern due to color difference due to difference in an optical pathlength can be suppressed. As a result, as deterioration in opticalcharacteristic due to an appeared electrode pattern can be suppressed,deterioration in characteristic of the display device with the touchpanel 20 mounted therein can be suppressed.

Still further, when a defect is caused in the first portion 1 a (bridgeportion) formed on the upper layer, the defect can be repaired bycarrying out again a process for forming the first portion 1 a. That is,deterioration in optical characteristic due to an appeared electrodepattern can be suppressed so that processability can be improved.

However, in the touch panel shown in FIGS. 6 to 8, formation of an upperlayer electrode (the first portion 1 a of the electrode 1X) on theinsulating film 12 is inefficient in view of process, material, andcosts as requiring material and process similar to those required information of a lower layer electrode (the second portion of theelectrode 1X and the electrode 1Y) under the insulating film 12,although the area for formation is very small. Such inefficiency needsto be addressed, or otherwise causing increase of the cost of a displaydevice with the touch panel mounted therein.

In view of the above, the present inventor takes notice of the wiringelectrically connected to the matrix electrodes (electrodes 1X and 1Y)in achieving the present invention.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a technique capable ofreducing costs of a touch panel-equipped display device. The abovedescribed and other objects and new characteristics of the presentinvention will become obvious in view of the description in thisspecification and the accompanying drawings.

A representative invention among those disclosed in this applicationwill be outlined as below.

-   (1) According to one aspect of the present invention, there is    provided a touch panel-equipped display device comprising a display    panel; and an electrostatic capacitance type touch panel arranged on    a surface of the display panel, the surface closer to a viewer,    wherein the touch panel includes a plurality of first electrodes    formed on the substrate, extending in a first direction and being    aligned in parallel in a second direction intersecting the first    direction, a plurality of second electrodes formed on the substrate,    extending in the second direction so as to intersect the first    electrodes and being aligned in parallel in the first direction, and    a plurality of wirings electrically connected to the plurality of    respective first electrodes and the plurality of respective second    electrodes, each of the plurality of first electrodes has a first    portion formed on a layer different from a layer on which the second    electrodes are formed and intersecting the second electrodes, and a    second portion formed on the layer on which the second electrodes    are formed, but separated from the second electrodes, the second    electrodes and the second portions of the first electrodes are    formed on a layer upper than a layer where the wirings are formed,    and the first portions of the first electrodes are connected to the    second portions in a contact hole formed on an insulating film    between the first portions and the second electrodes, and formed on    the layer where the wirings are formed.-   (2) In the above described touch panel-equipped display device (1),    the second electrodes and the second portions of the first    electrodes may be formed using electrically conductive transparent    material, while the wirings and the first portions of the first    electrodes may be formed using electrically conductive metal    material having a lower resistance value than that of the second    electrodes and the second portions of the first electrodes.-   (3) In the above described touch panel-equipped display device (1)    or (2), the second electrode may have a portion, located between the    adjacent first electrodes, wider than another portion thereof which    intersects the first electrode, and the second portion of the first    electrode may be formed wider between the adjacent second electrodes    than the first portion of the first electrode.-   (4) In any of the above described touch panel-equipped display    devices (1) to (3), the display panel may have a display area where    a plurality of pixels are arranged, and a non-display area provided    around the display area; the first and second electrodes may be    arranged in an area opposed to the display area of the display    panel; and the wirings may be arranged in an area opposed to the    non-display area of the display panel.-   (5) Any of the above described touch panel-equipped display    devices (1) to (4) may further comprise a protective film formed on    the substrate so as to cover the first and second electrodes.

According to the present invention, cost reduction for a touchpanel-equipped display device can be attained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an electrode pattern of a touch panelmounted in a touch panel-equipped display device according to oneembodiment of the present invention;

FIG. 2 is an enlarged plan view showing a part shown in FIG. 1;

FIG. 3 is a cross sectional view showing a cross sectional structurealong the line III-III in FIG. 1;

FIG. 4 is a cross sectional view showing a cross sectional structurealong the IV-IV in FIG. 1;

FIG. 5 is a block diagram showing a schematic structure of a touchpanel-equipped display device according to one embodiment of the presentinvention;

FIG. 6 is a plan view showing an electrode pattern of an electrostaticcapacitance type touch panel for which a patent application has beenfiled by the present applicant;

FIG. 7 is a cross sectional view showing a cross sectional structurealong the line VII-VII in FIG. 6; and

FIG. 8 is a cross sectional view showing a cross sectional structurealong the line VIII-VIII in FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

In the following, an embodiment of the present invention will bedescribed in detail referring to the accompanying drawings. Note that,in all drawings for explaining an embodiment of the present invention, amember having an identical function is referred to by an identicalreference number and an explanation thereof is not repeated.

In this embodiment, an example in which the present invention is appliedto a touch panel-equipped display device having a touch panel on, e.g.,a liquid crystal display panel as an example of a display panel isdescribed.

FIGS. 1 to 5 are drawings related to a touch panel-equipped displaypanel according to one embodiment of the present invention.

FIG. 1 is a plan view showing an electrode pattern of a touch panelmounted in a touch panel-equipped display device. FIG. 2 is an enlargedplan view showing a part shown in FIG. 1. FIG. 3 is a cross sectionalview showing a cross sectional structure along the line III-III inFIG. 1. FIG. 4 is a cross sectional view showing a cross sectionalstructure along the line IV-IV in FIG. 1. FIG. 5 is a block diagramshowing a schematic structure of a touch panel-equipped display device.

Note that FIG. 5 shows a cross sectional structure of the touch panel 20along the line V-V in FIG. 1.

A touch panel-equipped display device in this embodiment, as shown inFIG. 5, comprises a liquid crystal display panel 30, an electrostaticcapacitance type touch panel 20 arranged on a surface of the liquidcrystal display panel 30, the surface closer to a viewer, and abacklight 40 arranged under a surface of the liquid crystal displaypanel 30, the surface farther from the viewer. As a liquid crystaldisplay panel 30, a liquid crystal display panel of, e.g., IPS type, TNtype, VA type, or the like, is used. The liquid crystal display panel 30has a display area where a plurality of pixels are arranged in a matrixand a non-display area provided around the display area. Each of theplurality of pixels has a pixel electrode and an opposed electrode. Inthe non-display area, a light shielding film, such as a black matrix, isprovided.

The touch panel 20, as shown in FIGS. 1 to 4, comprises a plurality ofelectrodes 1X and a plurality of electrodes 2Y. The electrodes 1X extendin a first direction (e.g., the X direction) and are aligned in parallelin a second direction (e.g., the Y direction) intersecting the firstdirection at a predetermined alignment pitch. The electrodes 2Y extendin the second direction so as to intersect the electrodes 1X and arealigned in parallel in the first direction at a predetermined alignmentpitch.

Each of the plurality of electrodes 2Y is formed having an electrodepattern in which a plurality of first portions 2 a and a plurality ofsecond portion 2 b, each being wider than the first portion 2 a, arealternately arranged in the second direction. Each of the plurality ofelectrodes 2Y is arranged on the surface of the substrate 11, closer tothe viewer, via an insulating film 12, and further covered by aprotective film 13 formed thereon. As the substrate 11, a transparentinsulating substrate, e.g., glass, or the like, is used.

Each of the plurality of electrodes 1X is formed having an electrodepattern in which a plurality of first potions 1 a and a plurality ofsecond portions 1 b, each being wider than the first portion 1 a, arealternately arranged in the first direction. The first portion 1 a ofeach of the plurality of electrodes 1X is formed on an electricallyconductive layer different from that on which the electrode 2Y isformed, and as viewed two-dimensionally intersects the first portion 2 aof the electrode 2Y. The second portion 1 b of each of the plurality ofelectrodes 1X is formed on the same electrically conductive layer asthat on which the electrode 2Y is formed, but separated from theelectrode 2Y. In this embodiment, the first portion 1 a of the electrode1X is formed on a layer lower than that of the electrode 2Y.

Similar to the electrode 2Y, the second portion 1 b of each of theplurality of electrodes 1X is arranged on the surface of the substrate11, closer to the viewer, via the insulating film 12, and covered by theprotective film 13 formed thereon. The first portion 1 a of each of theplurality of electrodes 1X is arranged on the surface of the substrate11, closer to the viewer, and covered by the insulating film 12 formedthereon.

The first portion 1 a of the electrode 1X, as viewed two-dimensionally,intersects the first portion 2 a of the electrode 2Y, and electricallyand mechanically connected to two second portions 1 b, respectively,which are arranged adjacent to each other with the first portion 2 ain-between, in a contact hole 12 a formed on the insulating film 12which serves as an inter-layer insulating film between the first portion1 a of the electrode 1X and the electrode 2Y.

That is, each of the plurality of electrodes 1X is formed on anelectrically conductive layer different from that on which the electrode2Y is formed, and has the first portion 1 a intersecting the electrode2Y and the second portion 1 b formed on the same electrically conductivelayer as that on which the electrode 2Y is formed, but separated fromthe electrode 2Y. The first portion 1 a of the electrode 1X iselectrically connected to the second portion 1 b of the electrode 1X inthe contact hole 12 a formed on the insulating film 12 between the firstportion 1 a and the electrode 2Y.

The second portion 2 b of the electrode 2Y is arranged, as viewedtwo-dimensionally, between the first portion 1 a of two adjacentelectrodes 1X. The second portion 1 b of the electrode 1X is arranged,as viewed two-dimensionally, between the first portions 2 a of twoadjacent electrodes 2Y.

That is, the electrode 2Y has a portion, located between two adjacentelectrodes 1X, wider than that of another portion thereof intersectingthe electrodes 1X, while the electrode 1X has a portion, located betweentwo adjacent electrodes 2Y, wider than that of another portion thereofintersecting the electrodes 2Y.

The touch panel 20 comprises a central area where a plurality ofelectrodes 1Y and 1X are arranged and a peripheral area provided aroundthe central area. As shown in FIG. 1, a plurality of wirings MLelectrically connected to each of the plurality of electrodes 1Y and 1Xare provided in the peripheral area of the touch panel 20. The pluralityof respective wirings ML electrically connect the plurality ofrespective electrodes 1Y and 1X to a touch position control circuit.

The central area of the touch panel 20 is arranged so as to correspondto the display area of the liquid crystal display panel 30, while theperipheral area of the touch panel 20 is arranged so as to correspond tothe non-display area of the liquid crystal display panel 30. That is,the plurality of electrodes 1X and 1Y of the touch panel 20 are arrangedin an area opposed to the display area of the liquid crystal displaypanel 30, while the plurality of wirings ML are arranged in an areaopposed to the non-display area of the liquid crystal display panel 30.

As shown in FIG. 3, each of the plurality of wirings ML is arranged onthe surface of the substrate 11, the surface closer to the viewer, andcovered by an insulating film 12 formed thereon. The first portion 1 aof each of the plurality of electrodes 1X is formed on the sameelectrically conductive layer as that where the plurality of wirings MLare formed. That is, the first portion 1 a of each of the plurality ofelectrodes 1X is formed simultaneously with the plurality of wirings ML,which are formed by patterning an electrically conductive film. Each ofthe plurality of wirings ML is electrically connected to a correspondingelectrode (electrodes 1Y and 1X) at a terminal of the electrode(electrode 1Y and 1X) via a connection portion 12 b formed on theinsulating film 12, as shown in FIG. 3.

Note that the second portion 1 b of the electrode 1X and the electrode1Y are formed using electrically conductive transparent material, e.g.,ITO (Indium Tin Oxide), or the like, having high transmissivity.Meanwhile, the first portion 1 a of the electrode 1X and the wiring MLare formed using electrically conductive metal material, e.g., silveralloy, having a lower resistance value than that of the second portion 1b of the electrode 1X and the electrode 1Y.

Note that, in FIG. 5, presence of capacitances C1, C3 between the finger50 of a viewer and the electrode 1X and that of a capacitance C2 betweenthe finger 50 of a viewer and the electrode 2Y are schematicallyillustrated. The touch panel 20 according to this embodiment detects acapacitance difference in coupling capacitance between the electrodes 1Xand 2Y to thereby detect the touch position coordinates of a position onthe touch panel 20, touched by the finger 50 of a viewer.

In the following, a method for manufacturing the touch panel 20 in thisembodiment is described referring to FIGS. 1 to 4.

Initially, a first electrically conductive film is formed on the surfaceof the substrate 11, closer to a viewer, using electrically conductivemetal material (e.g., silver alloy) having a lower resistance value thanthat of electrically conductive transparent material (e.g., ITO).

Subsequently, a first mask including a wiring pattern and an electrodepattern is formed on the first electrically conductive film, using,e.g., positive resist, and the first electrically conductive film isetched using the first mask as an etching mask to thereby form thewiring ML and the first portion 1 a of the electrode 1X on the substrate11.

Thereafter, the first mask is removed, and an insulating film 12 isformed using, e.g., negative resist on the substrate 11 including thewiring ML and the first portion 1 a of the electrode 1X. At thisprocess, the wiring ML and the first portion 1 a of the electrode 1X arecovered by the insulating film 12.

Thereafter, the contact hole 12 a and the connection portion 12 b areformed at suitable positions on the insulating film 12, and a secondelectrically conductive film is then formed using electricallyconductive transparent material (e.g., ITO) on the insulating film 12including inside the contact hole 12 a and the connection portion 12 b.

Further, a second mask including an electrode pattern is formed on thesecond electrically conductive film, using, e.g., positive resist, andthe second electrically conductive film is etched using the second maskas an etching mask to thereby form the second portion 1 b of theelectrode 1X and the electrode 1Y on the insulating film 12. At thisstep, the second portion 1 b on the upper layer is electrically andmechanically connected to the first portion 1 a on the lower layer inthe contact hole 12 a. Further, the first portion 1 a on the lower layerintersects the first portion 1 a of the electrode 2Y on the upper layer.Also, the respective ends of the electrodes 1X and 1Y are electricallyand mechanically connected to the corresponding wirings ML on the lowerlayer via the connection portion 12 b.

Thereafter, the second mask is removed, and the protective film 13 isformed, using, e.g., negative resist on the insulating film 12 includingthe second portion 1 b of the electrode 1X and the electrode 1Y. Withthe above, the structure shown in FIGS. 1 to 4 is formed. At this step,the second portion 1 b of the electrode 1X and the electrode 1Y arecovered by the protective film 13.

Note that formation of the peripheral wiring pattern can be carried outappropriately between the above described steps.

Note that, for the touch panel shown in FIGS. 6 to 8, formation of anupper layer electrode (the first portion 1 a of the electrode 1X) on theinsulating film 12 requires similar material and process to that whichis required in formation of a lower layer electrode (the second portionof the electrode 1X and the electrode 1Y), although an area forformation is very small.

On the contrary, for the electrostatic capacitance type touch panel 20according to the present invention, as shown in FIGS. 1 to 4, the firstportion 1 a of the electrode 1X is formed on the same electricallyconductive layer as that on which the wiring ML is formed. Such anelectrode structure can eliminate the layer required for the firstportion 1 a of the electrode 1X in the touch panel shown in FIGS. 6 to8, and therefore involved material and process can be omitted. Thisenables production of a further inexpensive touch panel, and thusachieves cost reduction for a touch panel-equipped display device with atouch panel mounted therein.

Further, as majority (except the first portion 1 a of the electrode 1X)of the matrix electrodes comprising the electrodes 1X and 1Y are formedon the same layer, using electrically conductive transparent material,problematic appearance of an electrode pattern due to color differencedue to difference in light path length for reflected light anddistortion of the insulating film and the protective film can besuppressed so that preferable optical characteristic can be realized.

Still further, as the first portion 1 a of the electrode 1X is formedusing electrically conductive material (e.g., silver alloy) having alower resistance value than that of the electrode 2Y and the secondportion 1 b of the electrode 1X, lower resistance of one electrode linecomprising one electrode 1X can be attained.

Note that, although an example in which the first portion 1 a of theelectrode 1X and the wiring ML are formed on the same layer is describedin the above, obviously, the present invention can be applied to a casein which the first portion 2 a of the electrode 1Y and the wiring ML areformed on the same layer.

Further, although a touch panel-equipped display device having a touchpanel formed on a liquid crystal display panel as an example of adisplay panel is described in the above, obviously, application of thepresent invention is not limited to the above example, and the presentinvention can be applied to a touch panel-equipped display device havinga touch panel formed on a different type of display panel, such as anorganic EL display panel, an inorganic EL display panel, or the like.

Although an invention having been attained by the present inventor hasbeen specifically described based on the above described embodiment, thepresent invention is not limited to the above described embodiment andcan be modified in a variety of manners not departing from the gist ofthe present invention.

1. A touch panel-equipped display device, comprising: a display panel;and an electrostatic capacitance type touch panel arranged on a surfaceof the display panel, the surface closer to a viewer, the touch panelincluding: a substrate, a plurality of first electrodes formed on thesubstrate, extending in a first direction and being aligned in parallelin a second direction intersecting the first direction, a plurality ofsecond electrodes extending in the second direction so as to threedimensionally intersect the plurality of first electrodes and beingaligned in parallel in the first direction, and a plurality of wiringselectrically connected to the plurality of first electrodes and theplurality of second electrodes respectively, wherein each of theplurality of first electrodes has a first portion formed on a layerdifferent from a layer on which the plurality of second electrodes areformed and three-dimensionally intersecting one of the plurality ofsecond electrodes, and a second portion formed on the layer on which theplurality of second electrodes are formed, but separated from theplurality of second electrodes, the plurality of second electrodes andthe second portion are formed on a position higher than the wirings, andthe first portion is electrically connected to the second portionthrough a contact hole formed in an insulating film between the firstportion and the plurality of second electrodes, and is formed on thelayer where the wirings are formed.
 2. The touch panel-equipped displaydevice according to claim 1, wherein the plurality of second electrodesand the second portion are formed using electrically conductivetransparent material, and the wirings and the first portion are formedusing electrically conductive metal material having a lower resistancevalue than a resistance value of the second electrodes and the secondportion.
 3. The touch panel-equipped display device according to claim1, wherein each of the plurality of second electrodes has a portion,located between adjacent two electrodes of the plurality of firstelectrodes, wider than another portion thereof which three dimensionallyintersects the first portion, and the second portion is formed widerbetween adjacent two electrodes of the plurality of second electrodesthan the first portion.
 4. The touch panel-equipped display deviceaccording to claim 1, wherein the display panel has a display area wherea plurality of pixels are arranged, and a non-display area providedaround the display area; the plurality of first electrodes and theplurality of second electrodes are arranged in an area opposed to thedisplay area of the display panel; and the wirings are arranged in anarea opposed to the non-display area of the display panel.
 5. The touchpanel-equipped display device according to claim 1, further comprising aprotective film formed on the substrate so as to cover the plurality offirst electrodes and the plurality of second electrodes.